An old-fashioned Czech bread soup made from stale sourdough simmered with garlic and caraway, thickened with egg, and finished with cold butter and fresh parsley.
Add the bread. Bring 5 cups chicken broth to a boil in a pot. Add 3 slices sourdough bread cut into pieces.
Season and simmer. Lower the heat. Stir in 1 teaspoon salt, 1 teaspoon caraway seeds, and 3 cloves garlic, peeled and mashed. Cover and simmer gently for 20 minutes, until the bread softens into the broth.
Whisk in the eggs. Beat 2 medium eggs in a cup. Pour them into the hot soup in a thin stream, whisking constantly, so they set into fine, silky threads. Cook for about 1 minute.
Finish with butter. Remove from the heat source. Drop in 2 Tablespoon unsalted butter, cold, and stir gently until it melts into the soup.
Taste and serve. Add more salt if needed. Ladle into bowls and top with chopped parsley, and a little black pepper if you like.
Notes
Serves 6 as a light soup.
Bread: sourdough is best for its gentle tang; rye or a yeast-raised wheat-rye loaf also works. Avoid soft white sandwich bread, which turns mushy with no taste.
Eggs: keep the heat gentle once the eggs go in, and pour them in slowly while whisking diligently.
Broth: use chicken broth for a hearty bowl, or vegetable broth for a meatless, Lenten version.
Storage: keep in the refrigerator up to 2 to 3 days. The soup thickens overnight, so stir in a splash of broth or water as you reheat it gently. Do not freeze; the egg turns grainy and the bread goes mushy on thawing.